Development of Cold Tolerant Centipedegrass Cultivars.

Centipedegrass may exhibit reductions in growth and survival in response to subfreezing cold temperatures. A systematic germplasm collection was made in central and southern China in the fall of 1999 to broaden the centipedegrass germplasm base in the U.S. Ten seed from each Chinese accession were planted in pots (15.2 cm diameter) containing a Brownfield Sandy Clay Loam (loamy, mixed, superactive, thermic Arenic Aridic Paleustalfs; pH of 8.4) excavated from the Quaker Research Farm in Lubbock, TX. Each germinated seedling was transplanted into individual pots (15.2 cm diameter) containing the soil previously described. Each seedling became a “clonal” entry in the research trial. ‘Common’ and ‘TifBlair’ centipedegrass cultivars were added for comparison. Fertilizer (7N-7P₂O₅-7K₂O) was applied at time of transplant at 24 kg N ha^-1. Plants were irrigated with 5.0 cm water wk^-1 with an automated irrigation system. Natural light was supplemented with artificial light at 500 µmol m^-2 s^-1 photosynthetic photon flux in a 12-h day to approximate summer light intensity and photoperiod. Conditions in the greenhouse were maintained at day/night temperatures of 36/30 °C. Clonal entries were grown in the greenhouse for four months before being separated into three equal plugs and transplanted into bare soil at the Quaker Research Farm in June 2010. The trial design was a randomized complete block design with three replications of treatments. Centipedegrass was subjected to subfreezing temperatures in Lubbock, TX when temperatures dropped into single digits during several winter months in 2011. Digital photographs were taken after spring green-up on 4/15/2011 with a Nikon 10.0 megapixel camera mounted on a light box equipped with four incandescent light bulbs each with a light output of 172 µmol m^-2 s^-1. Digital images were analyzed using WinCam 2007 software to determine % turfgrass cover and % green leaf tissue. ‘Common’ centipedegrass did not survive the cold temperatures in 2011. However, ‘TifBlair’ exhibited 7% turfgrass cover and 27% green leaf tissue on 4/15/2011. The highest % turfgrass cover of the clonal entries was exhibited by ‘TC 427-7’ (63%) followed by (fb) ‘TC 437-33’ (49%) fb ‘TC 437-25’ (35%) and ‘TC 434-13’ (28%). All other clonal entries exhibited ≤ 23% turfgrass cover on 4/15/2011. The highest % green leaf tissue of the clonal entries was exhibited by ‘TC 437-26’ (72%) fb ‘TC 437-25’ (46%) fb ‘TC 428-6’ (43%) fb ‘TC 437-1’ (40%) and ‘TC 437-36’ (40%). All other clonal entries exhibited ≤ 35% green leaf tissue on 4/15/2011.